This method can help answer key questions in the engineer to surface field in understanding functional surface for tubular morphology and wettability. The main advantage of our approach is that it allows faster fabrication of multiscale nanomicro structures by using only an imprint process with an anodic aluminum oxide filter and a self-aggregation of nano fibers. After imprinting, the replicated surface patterns initially exhibited superhydrophilicity.
We can change the surface availability of the imprinted structures by using UV origin treatment and self-assembled monolayer coating. Obtain an anodic aluminum oxide, or AAO, filter with a pore size of 200 nanometers, height of 60 microns, and diameter of 25 milliliters. Clean the surface with polyethylene terephthalate, or PET film, with 99.8%acetone for five minutes, followed by 99.9.
isopropyl alcohol for five minutes. Completely dry the film for three minutes using an air gun. Next, place the PET film on a flat surface without contaminants.
Add a 0.1 milliliter drop of UV curable polyurethane acrylate type resin with a viscosity of 257.4 CPS on the surface. Place the AAO filter on the resin and press uniformly using a rubber roller with a diameter of 32 millimeters. The spread of the resin is visually confirmed.
The roller must be repeated and carefully pushed when pressing. The AAO filter is brittle and may break if excessive force is applied. After rolling, expose the specimen made with the PET and AAO filter to UV light with a wavelength of 365 nanometers for 30 seconds to cure the resin.
Then, immerse the cured specimen in 100 milliliters of two molar sodium hydroxide solution for 10 minutes to dissolve the filter. The SEM images show the surface and cross section of the structure. Clean the specimen with deionized water.
Then, completely dry it for three minutes using an air gun. Use energy dispersive x-ray analysis to confirm that sodium and aluminum are not detected and are completely etched. To perform the UV ozone treatment, first clean the specimen with nanomicro multiscale structures using isopropyl alcohol for five minutes and then deionized water for five minutes.
Dry the washed the specimen using an air gun for three minutes. Irradiate the specimen using UV rays for 60 minutes using UV ozone equipment with an intensity of 25 milliwatts per square centimeter. For OTS self-assembly, place the hot place inside the glovebox, and maintain a nitrogen environment for the vapor deposition process.
For filming purposes we will demonstrate the procedure in mock outside a glovebox. Place a beaker on the hot plate and add two milliliters of OTS solution to the beaker using a pipette. Cover the beaker with the glass or plate face on, with the specimen facing downward into the beaker.
Process for 60 minutes at 100 degrees Celsius before removing the specimen from the glovebox. To fabricate the functional surface by injecting lubricants, deposit approximately 0.2 milliliters per square centimeter of perfluorocarbon liquid on the OTS coated self-aggregated nanofiber assembly. Observe the wetting process of the perfluorocarbon using an optical microscope at five to 20 times magnification.
Finally, remove the excess perfluorocarbon liquid by placing the sample in a vertical position for a few hours. Multiscale nanomicro hybrid structures obtained by the imprint process and evaporation derived self-aggregation are shown here. It is difficult to measure the contact angle because of the superhydrophilicity of the fabricated surface.
Interestingly, after UV ozone treatment with sufficient time, the surface morphology and the surface wettability change from superhydrophilicity to hydrophobicity, with a contact angle of 126.8 degrees. Further more, the contact angle can be increased to 133.6 degrees by an additional coating of the self-assembled monolayer. After its development, this technique paved the way for researchers in the field of engineered surface to explore the surface functionality and morphology change with the self-assembly phenomenon and proper surface treatment.
Though this method can provide insight into the modification of the surface morphology and wettability, it can also be applied to other applications such as tissue via scalpel, environmental filters, catalyst disruptor, or with diffused optics, because of its larger scale porous structures.
